Induction of metallothionein and effect on essential metals in cadmium-loaded frog Xenopus laevis.

1. Cadmium (Cd) was administered orally as metallothionein (MT) in food or intramuscularly as MT and Cd2+ into a frog Xenopus laevis. 2. Oral administration resulted in low accumulation of Cd without affecting essential metal levels. 3. Intramuscular administrations of Cd as MT and Cd2+ resulted in accumulation of Cd in the kidney and in the liver and kidney, respectively, by inducing a Cd-binding protein which has properties characteristic of MT.